Heat sink for a rectifier

ABSTRACT

A heat sink for a rectifier which has two heat sink plates, multiple blind holes defined in the beat sink plates. Multiple assembly diodes each corresponding to one of the blind holes and multiple metal plates each received in the bottom of one of the blind holes and under the bottom of the nail connector. After the metal plates, diode chips and the nail connectors are placed in the blind hole of the heat sink plate, an insulating plate is filled into the blind hole to secure the location of the nail connector and the metal plate, such that because the contraction coefficient of the diode chip during the cooling process increases, the water filtration and particle contamination are avoided. Furthermore, the heat dissipation efficient of the rectifier is increased as well.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to a heat sink for a rectifier of an alternator, and more particularly to a heat sink for a rectifier with high performance of heat dissipation effect.

[0003] 2. Description of Related Art

[0004] Conventionally, rectifiers for alternators are well known in the art. Diodes are secured to heat sink surfaces by soldering or brazing respectively. When alternating current goes through diodes, heat will concentrate in the neighborhood of diodes in the heat sinks because diodes only attach to the heat sinks with a small area. Therefore, most part of heat sink may not play a good role for dissipating heat caused by rectifying due to the uneven distribution of heat. In conventional rectifiers, diodes connect either anodes or cathodes to the surface of the heat sink respectively by soldering or brazing. Therefore, most of heat will concentrate near the diodes in the heat sinks due to a small contact surface between diodes and the heat sinks. The heat dissipating efficiency is also limited because of the uneven distribution of heat.

[0005] In addition, diodes are respectively secured to the heat sink with either anodes or cathodes by soldering or brazing in conventional rectifiers. The attachment between the heat sink and diodes is supported by one small attaching end. That will possibly cause collapse after a long period of vibration or an unexpected huge impact. Also, in today's rectifier, diodes respectively connected to the heat sink are secured on an external small surface of the heat sink. Due to these reasons, diodes take high risk being water infiltrated during raining season. Another way is using press-fit diodes to solve the drawbacks mentioned above. As shown in FIG. 4, the metal case (63) is used to package the die (62) with the nail connector (61). The combinations are called press-fit diodes (6). A die (62) is completely sunk into the metal case (63) so that water filtrating and particle contamination are kept away. The press-fit diodes (6) are installed into the holes (21) and holes (31) from the bottom of the first sink plate (2) and the second sink plate (3). Because the press-fit diodes (6) are completely pressed into the holes (21,31), heat caused by rectifying can be well distributed around the first sink plate (2) and the second sink plate (3). Because the die (62) is completely secured, the drawbacks described above can be solved. However, there are still some problems needed to be answered. The metal case (63) should be made by casting or lathing process. This makes the cost higher than before. The press-fit diodes (6) must be formed firstly before they are pressed into holes (21,31), this will increase labor cost. In addition, when press-fit diodes (6) are installed into holes (21,31), gaps exiting between metal case (63) and sink plates (2,3) are formed, this will significantly cut down the heat dissipating efficiency.

[0006] Furthermore, the conventional diodes involve manual assembly and then pressed into the heat sink of the rectifier, this will increase manufacture cost.

[0007] It is an objective of invention to provide a heat sink for a rectifier to mitigate and/or obviate the aforementioned problems.

SUMMARY OF THE INVENTION

[0008] The primary objective of the invention is to provide an improved heat sink for a rectifier to averagely distribute heat produced by diodes. In the heat sink, blind holes are created for dice of diodes. Diodes can be formed and completely sunk into the main body of the heat sink. Furthermore, metal plates made of such as copper are placed in the bottom of the blind holes before the diodes are sunk into the blind holes. Therefore the dice packaging of diodes can be achieved at the same time during rectifier manufacturing process. Because diodes are built into blind holes in the heat sink and the copper plate is placed under the diode, the heat on diodes can be well distributed around the heat sink. Therefore, heat dissipation of heat sinks will be more efficient with the improved structure when compared with the prior art.

[0009] Another objective of the present is to provide an improved heat sink in which blind holes are created for completely sinking dice of diodes. Dice of diodes can be completely placed into the blind holes after the copper plate is placed in the bottom of the blind holes, and then an insulating material is filled into the spaces between the dice and the heat sinks. Therefore, during heat sink manufacturing, diodes packaging process is also accomplished in the same time.

[0010] Still another objective of the invention is that the dice of diodes are completely built in the blind holes and then sealed by the insulating material. With this arrangement and the change of shape of the copper to dish, water infiltrating and particle contamination can be prevented and diode protection is enhanced.

[0011] Other objects, advantages and novel features of invention will become more apparent from the following detailed description when taken in conjunction with accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a perspective view of the heat sink in accordance with the present invention;

[0013]FIG. 2 is an exploded perspective view of the first heat sink plate in accordance with the present invention;

[0014]FIG. 3 is a cross sectional view taken along line A-A of FIG. 1; and

[0015]FIG. 4 is an exploded perspective view of a conventional heat sink.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

[0016] Referring to FIG. 1, a heat sink (1) constructed in accordance with the present invention is shown. The heat sink (1) is composed of a first heat sink plate (2) and a second heat sink plate (3). Multiple blind holes (21,31) are defined respectively in the first heat sink plate (2) and the second heat sink plate (3) for embedding metal plates (43) and diode chips (42) made of such as copper or the like that has high expansion coefficient, as shown in FIG. 2. Each assembly diodes (4) comprises a nail connector (41), a diode chip (42) and a metal plate (43). That is, before the nail connectors (41) are placed into the corresponding blind holes (31) in the second heat sink plate (3), the metal plates (43) are placed into the blind holes (31) in the second metal plate (3).

[0017] With reference to FIG. 3, it is to be noted that when the blind holes (31) in the second heat sink (3) is defined, one of the metal plates (43) is placed in the blind hole (31). Thereafter, one of the nail connectors (41) is placed on the top of the diode chip (42) and metal plate (43) and then the blind hole (31) is seal with an insulating material (5) to completely sink the assembly diode (4) the blind hole (31).

[0018] After the assembly diode (4) is completely sunk in the blind hole (31) in the second heat sink plate (3), the insulating material (5) is filled into the blind hole (31) to securely position the location of the nail connector (41) and the metal plate (43). It is to be noted that the diode chip (42) made of copper has high expansion coefficient. That is, when the diode chip (42) of copper is cooled, its contraction coefficient is changed from 1.65-1.7 to 2.0-2.5. The change of the contraction coefficient of the diode chip (42) means that during the fabrication of the heat sink of the rectifier, the cooling of the heat sink plates (2,3) will increase the contraction of the diode chip (42) of copper, such that water infiltrating and particle contamination can be avoided.

[0019] It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

What is claimed is:
 1. A heat sink for a rectifier comprising: a first heat sink plate; a second heat sink plate securely connected with the first heat sink plate and having multiple blind holes defined therein; multiple metal plates each corresponding to and received in one of the multiple blind holes; multiple diode chips each corresponding to one of the metal plates; multiple nail connectors each corresponding to one of the metal plates and received in a corresponding one of the blind holes; and an insulating material filled in one of the blind holes to secure the location of the nail connector and the metal plate in each of the blind holes.
 2. The heat sink as claimed in claim 1, wherein each of the nail connectors is placed in the blind hole and on top of the meal plate.
 3. The heat sink as claimed in claim 1, wherein the diode chip is made of copper. 